Extended interaction device tuned by movable delay line structure

Abstract

A resonant cavity arranged for an electron beam to pass therethrough, is made of two spaced apart parallel substantially planar members movable with respect to each other in a direction perpendicular to their major surfaces, at least one of said members having a delay line structure on its inner face within the gap between said two members. Means are arranged for moving the members relative to each other so as to vary the spacing between said members, whereby the oscillation frequency is tuned easily. The resonant cavity can be used to realize wide-band extended interaction oscillators and klystron amplifiers.

What is claimed is: 
     
       1. An extended interaction oscillator or klystron amplifier cavity comprising a resonant cavity arranged for an electron beam to pass therethrough, said cavity being made of two spaced apart parallel planar members said planar members being movable with respect to each other in a direction perpendicular to their major surfaces, at least one of said members having a delay line structure on its inner face within the gap between said two members, means arranged for moving the members relative to each other so as to vary the spacing between said members, thereby to tune the oscillation frequency. 
     
     
       2. A device according to claim 1, wherein said means for moving the members relative to each other comprises a piezo-electric crystal mounted to a support, one of said members being attached to said piezo-electric crystal. 
     
     
       3. An extended interaction oscillator or klystron amplifier comprising an oscillator or klystron cavity comprised of a resonant cavity made of two spaced parallel, substantially planar members movable with respect to each other in a direction perpendicular to their major surfaces, at least one of said members having a delay line structure on its inner face within the gap between said two members, means arranged for moving the members relative to the each other so as to vary the spacing between said members, thereby to tune the oscillation frequency; a cathode arranged for producing an electron beam to enter and pass through the gap between said two members;   a collector arranged for collection the electron beam after it has passed through said gap; and   output coupling means arranged to couple the R.F. output exiting the resonant cavity to an output circuit.   
     
     
       4. A device according to claim 3, wherein the output coupling means comprises an iris cut in the cavity wall, and quasi-optical lens means arranged to focus the R.F. output radiated from said iris into an output beam. 
     
     
       5. A device according to claim 3, wherein the output coupling means comprises an output resonant cavity arranged for being traversed by the R.F. beam exiting the oscillator cavity and for resonating at the oscillator frequency.